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Mig welding copper

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I'm completely new at this so I'll try not to ramble. I'm building a copper sink out of .064 copper and I'm welding (just learning to weld also) it with an old Cebora 200 amp welder, cranked all the way up and wire feed about as fast as it will go I think about 350-400 IPM, using .035 deoxydized copper wire and 100 percent argon at 40CFH. It works 1-1/2" at a time before burn thru, but there is a huge amount of soot covering the weld and about an inch of the metal on either side. There is also lots of splatter at the start of the weld, Is this normal?

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Well I've never welded copper before or even thought of it so I'm probably talking out of my backside. On mild steel a 200 amp welder cranked will blow holes in very short order. I would try running somewhere around 50 amps and slow your wire speed to match. You surely have some scraps use them for practice. Good luck and I would like to see some of the welds.

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We used to weld 1/8" copper on a VERY regular basis here but have since shut down the plant where it was used. After much frustration we went to welding with TIG and using a light coating of flux. The flux you need is Bay State #11. You can also weld 316L SS to copper by this same procedure. Buff the area to be welded, lightly flux, weld. Helium is an excellent shield gas for welding thicker copper as it produces a much hotter weld arc but for your application 100% argon is good. If you are set on welding with the MIG process you may want to try to make your welds more down-hill instead of flat. As for the "black soot", buffing the area to be welded may help or you may need to go to a tri-mix shielding gas---something like 92-6-2---argon-CO2-oxy. Like I mentioned before, we found the welds to be much better using the TIG process and flux. I've been at this welding thing since 1973. Good luck!

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I have not welded copper with a mig or tig but have welded aluminum, stainless, and steel with both, and the tig just makes a cleaner weld, also less warping. I am sure that it would be just as well on the copper.

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Thanks a bunch for the info. I would love to TIG it but this a poor boy operation and the old used mig welder is what I have to work with. The welds are fine and penetrate without burn thru if I weld an inch, skip an inch then come back and fill in the skips. The soot doesn't seem to be a problem and you can actually weld right thru it, (you just can't see where you're going) so I wire brush it off, but man it is some ugly welding no matter how you do it.

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its hard to weld thin sheet in one pass, most people when working with the thin stuff put a small weld skip a bit small weld like - - - - - all the way down the weld, work way around repeat process (filling in gaps a little at a time) over and over again until its completly welded, helps with heat buildup and usually looks pretty good
hope this helps

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PBARNHART, Not sure but I would think that it would work. Just make sure not to have too much penatration as this would fuse your backing plate to your piece you are welding. Possibly if you have say 3/8" or thicker backing plate it would be better, it would draw the heat faster but not get so hot that it would weld to the working piece. Does this make sense?

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i'm not sure if i'm too late with this reply, i only just joined up . but any way. do you have to weld it? that is with a mig/tig ( i also recomend tig by the way ,you can get a nice weld) i've spent a few years working as a copper smith, why don't you silver solder it? that would be the easiest, some phos. copper.(low grade silv. sold.the same stuff they use to join copper pipes together) no need for flux if your joining copper to copper and relatively low heat. plus cheap, all you need is an oxy torch. if your worried about strength, remember all your carbide tips are soldered on .might be easier than welding?



hot in OZ , 34cel, very humid . need rain ,lots of rain!!!!

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I never weld copper anymore. I only use the Harris #0 Phos rods and use my Tig torch for heat. You need less amps this way because of the lower melting point of the rod. The connection is super strong and the color match is perfect. If you don't have a tig, an O/A torch will work fine as well just not as fast. The Tig also makes tacking things in place easier as well.

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Many people may think that Copper Sinks are soft or fragile but thats not true. They are sturdy enough to substitute a regular, series made, stainless steel sink. Copper plates are sturdy enough that even bathtubs are fabricated entirely on copper. Thanks to the patination process they wont acquire a greenish color or get rusty with time and use.

Edited by mod07
corrected link

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I am not a weldor by any means, but my instructor showed me how to weld thin-gauge metals with mig using short pulses on the trigger. kind of like squeeze-one-two release. squeeze-one-two release. and so forth. once I picked up the rhythem, things went really quick with minimal heat build-up

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TURN THAT GAS FLOW DOWN!!!! You only need 15-25CFH. Only on SPECIAL occasions do you need high gas flow like that. When you turn the gas up that high, you are more than likely creating a venturi affect. What this is, is the somewhat the same principal as the shower curtain moving in on you when the water is running. The gas is flowing down at such a fast rate that it is actually pulling atmospheric gasses into the weld area. This is not wanted! This is very likely the cause of the black soot on your weld. Plus your settings are not right. Just because the voltage is all the way up and the wire feed speed all the way up doesn't necessarily make it a balanced welding, shall we say, "equation". Plus, how thick is the material you are welding?? The wire may be too thick for the application. I agree completely with Thomas Dean, weld downhill. You should get some scrap copper the same thickness and practice first before you go welding the "good stuff" for real.

-Hillbilly

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A 4kg roll of copper silicon bronze wire will probably set you back upwards of £160, on top of that you will need a decent machine to run it, I had SAF synergic set with a proper program in it, so its likely that trying to use a basic welder will not end well. You may find it cheaper and less frustrating to just recruit another pair of hands to position and hold the parts in place while you braze them, tig brazing would be ideal for this.

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3 hours ago, drossall said:

tig brazing would be ideal

I agree, either that or oxy acc brazing would be my choice.

Welcome aboard, I always suggest this thread to get the best out of the forum. It is full of tips like editing your profile to show your location and how to keep the moderators happy.:) READ THIS FIRST

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